Halphenyllithium initiators for conjugated diene polymerization

ABSTRACT

A method of polymerizing conjugated dienes which employs a halophenyllithium initiator prepared from the interreaction of an alkyllithium and a bromoiodobenzene is disclosed.

Staies Patem Trepka et al.

[54] HALPHENYLLITHIUM INITIATORS FOR CONJUGATED DIENE POLYMERIZATION[72] inventors: William J. Trepka; Richard J. Sonnenleld, both of c/oPhillips Petroleum Company, Bartlesville, Okla.

22 Filed: Aug. 3, 1970 21 Appl. No.: 60,610

[52] U.S. CI. ..260/665 R, 252/431 R, 260/942 M [51] Int. Cl. ..C07l1/02, C08d 3/04 [58] Field of Search ..260/665 R [56] References CitedUNITED STATES PATENTS 3,067,265 12/1962 Frampton et al, ..260/ 6 5R [4 1Sept. 26, 1972 3,082,264 3/1963 West et al. ..260/665 R 3,429,829 2/1969Kahle ..260/665 R OTHER PUBLICATIONS Oikawa Chem. Abstracts 59(1963)Columns 14013-4.

- Primary Examiner-Tobias E. Levow Assistant Examiner-A. P. DemersAttorney-Young and Quigg 6 Claims, No Drawings HALPHENYLLITHIUMINITIATORS FOR CONJUGATED DIENE POLYMERIZATION This invention relates tohalophenyllithium catalysts, or initiators.

In one of its more specific aspects, this invention relates to a processand initiator for the'polymerization of a conjugated diene, andparticularly of butadiene,

isoprene and mixtures thereof which involves contact- .which comprisesthe reaction product of an alkyllithium and a bromoiodobenzene compound.

Also, according to this invention there is provided a method for thepolymerization reaction with an initiator comprising a reaction productof an alkyllithium and a bromoiodobenzene compound selected from thegroup consisting of 1-brorno-3-iodobenzene and 1- bromo-4-iodobenzene.

Accordingly, it is an object of this invention to provide a more simplyprepared butadiene and isoprene polymerization initiator.

It is another object of this invention to provide a polymerizationprocess which produces polymers having properties dififerentfrom thoseproduced from the same monomer by other initiators.

These and other objects; of this invention will become evident in lightof the following disclosure.

The method of this invention is employable under those operatingconditions under which reactions polymerizing conjugated dienes areconventionally conducted. The method of this invention is particularlyapplicable to the polymerization of butadiene and isoprene and to theuse of the reaction product of a butyllithium with 1-bromo-3-iodobenzeneand l-bromo- 4-iodoben zene. Subsequent examples which illustrate theinvention and which employ these materials arenot to be considered aslimiting the invention thereto, however.

The initiators of this invention are prepared in that mannerconventionally employed in producing similar materials. Thesealkyllithium compounds contain in the range of one to carbon atoms.

Specifically, the product of l-bromo-S-iodobenzene and butyllithium canbe prepared by introducing an organic solvent, for example, toluene,into a reactor,

. purging the reactor with nitrogen and then adding 1-bromo-3-iodobenzene and the butyllithium. The amount of toluene will besufficient to act as a reaction diluent for the other components. Themixture is agitated at about 122 F. for about 3 hours, after which thereis produced. a solid product which can be employed in the reactionmixture in which it is formed, in which it is known as being in theunwashed" state. Al-

, ternately, it can be separated from the reaction mixture, washed witha liquid such as cyclohexane in which it is negligibly soluble andemployed in a liquid suspending medium, in which instance it is known asbeing in the washed state.

The product of 1-bromo-4-iodobenzene and butyllithium is prepared in thesame manner as that employ- :ing '1-bromo-3-iodobenzene and employs thesame mole relationship between the toluene and the reactants, and boththe washed and the unwashed reaction product can be recovered. Reactionproducts of the bromoiodobenzene and other alkyllithiums can be preparedby the above method.

Preferably, the molar ratios of alkyllithium to bromoiodobenzene will be0.9: l to 2.3: 1.

EXAMPLE 1 Reaction products were recovered from two individual runs inwhich 1-bromo-3-iodobenzene was reacted with butyllithium. A thirdreaction product, for comparison purposes, was recovered from thereaction of 1,3-dibromobenzene with butyllithium. In each instance, thebenzene dihalide and butyllithium were added to the toluene and themixture was agitated for 3 hours, except for Mixture D which was reactedfor 2 hours, at 122 F. Reaction mixtures and results were as Theunwashed reaction mixtures A, B, and C were employed in thepolymerization of isoprene in a cyclohexane diluent for various reactiontimes at 158 F.

ln eachinstance, to 1000 parts of cyclohexane per hundred parts ofmonomer (phm) were added parts of isoprene and 1 of the unwashedinitiators A, B and C, in the concentration of milliequivalents per 1 00parts by weight of monomer as shown below. The reaction was temiinatedand a conventional antioxidant,2,2'-methylenebis(4-methyl-7-tert-butylphenol) in the amount of 1 partper 100 parts of rubber (phr) was added. The polymer was coagulated withalcohol and the dried polymers had the following properties.

(a) Heterogeneity Index. The ratio of the weight average molecularweight (M,,) to the number average molecular weight (M,,) as determinedby Gel Permeation Chromatography (GPC).

EXAMPLE II A series of initiators was prepared in which the butyllithiumconcentration was varied in relation to the quantity ofl-bromo-3-iodobenzene, from a mole ratio of 1.25 to 1.75. One initiatorwas prepared for comparison purposes from 1,3-dibromobenzene. Reactionconditions and reactant concentrations were as indicated in Table 111.Temperature was 122 F. Reaction time was 3 hours. The procedure was thesame as in Example I.

TABLE III Initiator Designation Reaction Mixture, mmoles E F G H Toluene560 560 560 S60 l-Bromo-3-iodobenzene 10 10 10 1,3-Dibromobenzene 0 0 0Butyllithium 12.5 15.0 17.5 10 Product Property Normality 0.1570.1770.190 0.127

Alkalinity as butyllithium 85.6 81.4 73.8 82.6

The unwashed reaction mixtures E, F, G, and H were employed in thepolymerization of isoprene in a cyclohexane diluent according to theprocedure and recipe of Example 1 at constant reaction times of hours at158 F., with the results indicated in Table IV:

TABLE IV Product Analysis Reaction initiator, conversion Cis, 3,4 addn.inherent Mixture mhm viscosity These data indicate that a low inherentviscosity product of good cis content can be prepared with the 1.25 moleratio mixture (Initiator E) and that at higher mole ratios ofbutyllithium to dihalobenzene of the mixtures, higher initiatorconcentrations are required. A substantial improvement is demonstratedin lower inherent viscosity polymer produced by initiators of theinvention as compared to the prior art Initiator H.

EXAMPLE III In another series of reactions, initiators were formulatedby interreacting butyllithium and 1-bromo-4- iodobenzene according tothe procedure of Example I. The interreaction was conducted under theconditions and with the compositions indicated in Table V.

TABLE V Initiator Designation Reaction Mixture I L M Toluene, mmoles 560560 560 I-bromo-4-iodobenzene, mmoles l0 l0 l0 Butyllithium, mmoles 9 910 Time, Hours 2 0.25 0.25

Temperature, F. I22 77 77 Product Property Normality 0.125 0.1 16 0.133

Alkalinity as butyllithium 100 83.7 86.3

The reaction mixtures, I, L and M, were employed in the polymerizationof isoprene according to the procedure of Example I in a cyclohexanediluent at constant reaction times of 15 hours at 158 F., with theresults indicated in Table VI:

TABLE VI Product Analysis Reaction initiator, conversion Cis 3,4 addn.Inherent Mixture mhm viscosity 1 2.50 76 90 5.3 1.30 L 2.50 66 93 6.01.28 M 2.25 71 96 5.6 1.97 M 2.50 82 98 5.8 1.78

The above data indicate the operability of the initiator and method ofthis invention when employing an initiator formulated from theinterreaction of l-bromo-4- iodobenzene. These data further indicatethat those initiators formed from l-bromo-4-iodobenzene are more activewhen prepared at temperatures of about 77 P. if prepared of reactionmixtures comprising an equal molar ratio of butyllithium to1-bromo-4-iodobenzene.

EXAMPLE IV lnitiators were prepared by interreaction oflbromo-3-iodobenzene with butyllithium and by the interreaction of1-bromo-4-iodobenzene with butyllithium. These were prepared at l to 1mole reactant ratio at 77 F. according to the procedure of Example I.

The initiators were then employed in the polymerization of butadiene ina reaction mixture comprising 760 phm cyclohexane at C. Results were asindicated in Table VII:

TABLE VII Product Analysis initireaction viinheator, time, conv., cistrans nyl rent initiator mhm hrs. visc.

l-Bromo-4- iodobenzene+ 2.00 24 41 84.9 10.6 4.5

1.57 Butyllithium 2.50 24 50 82.2 12.9 4.9

1.40 l-Bromo-3- iodobenzene 1.00 3 86 58.3 34.0 7.7

2.39 Butyllithium 2.50 3 89 48.8 42.5 8.7

The above data illustrate the operability of the initiator and method ofthis invention in the polymerization of butadiene.

The above data illustrate the operability of the initiators and themethod of this invention as directed to the polymerization of isopreneand butadiene.

Summarily, the above data indicate that unexpected polymerizationproducts are realized when employing polymerization initiators of1-bromo-4-iodobenzene as compared to those results realized whenemploying 1 ,4-dibromobenzene.

It will be evident in light of the foregoing that various modificationscan be made to the initiators and method of this invention. Such,however, are considered as being within the scope of the invention.

What is claimed is:

1. An initiator for the polymerization of conjugated dienes whichconsists essentially of the reaction product of an alkyllithiumcontaining from one to carbon atoms and a bromoiodobenzene selected fromthe group consisting of l-bromo-3-iodobenzene and lbromo-4-iodobenzene.

2. An initiator for the polymerization of conjugated dienes whichconsists essentially of the reaction product of an alkyllithiumcontaining from one to 10 atoms and a bromoiodobenzene selected from thegroup consisting of l-bromo-3-iodobenzene and lbromo-4-iodobenzene, saidalkyllithium being employed with said bromoiodobenzene in a molar ratioof from about 0.911 to about 2.3: 1.

3. An initiator for the polymerization of conjugated dienes whichcomprises the reaction product of butyllithium and a bromoiodobenzene,said butyllithium being employed with said bromoiodobenzene in a molarratio of from about 0.9:1 to about 2.3:1, said bromoiodobenzene beingselected from the group consisting of l-bromo-3-iodobenzene andl-bromo-4- iodobenzene.

4. The initiator as defined in claim 3 in which said bromoiodobenzene is1-bromo-3-iodobenzene.

5. The initiator as defined in claim 3 in which said bromoiodobenzene is1-bromo-4-iodobenzene.

6. The initiator as defined in claim 3 in which said initiator isprepared from a l to 1 ratio of said butyllithium and saidbromoiodobenzene, said initiator being prepared at 25 C.

2. An initiator for the polymerization of conjugated dienes whichconsists essentially of the reaction product of an alkyllithiumcontaining from one to 10 atoms and a bromoiodobenzene selected from thegroup consisting of 1-bromo-3-iodobenzene and 1-bromo-4-iodobenzene,said alkyllithium being employed with said bromoiodobenzene in a molarratio of from about 0.9:1 to about 2.3:1.
 3. An initiator for thepolymerization of conjugated dienes which comprises the reaction productof butyllithium and a bromoiodobenzene, said butyllithium being employedwith said bromoiodobenzene in a molar ratio of from about 0.9:1 to about2.3:1, said bromoiodobenzene being selected from the group consisting of1-bromo-3-iodobenzene and 1-bromo-4-iodobenzene.
 4. The initiator asdefined in claim 3 in which said bromoiodobenzene is1-bromo-3-iodobenzene.
 5. The initiator as defined in claim 3 in whichsaid bromoiodobenzene is 1-bromo-4-iodobenzene.
 6. The initiator asdefined in claim 3 in which said initiator is prepared from a 1 to 1ratio of said butyllithium and said bromoiodobenzene, said initiatorbeing prepared at 25* C.